It appears as if Nikon has introduced a new Micro (macro) Nikkor lens designed for their DX format lineup of cameras. The new AF-S DX Micro-NIKKOR 40mm f/2.8G is a compact micro lens with a 1:1 magnification ratio. It features Nikon's SIC (Super Integrated Coating) to reduce flare, a built in SWM (Silent Wave Motor) for quick and quiet focusing, CRC (Close-Range Correction) technology for superior focusing at close distances using floating lens elements plus a M/A (manual/auto) focusing switch to quickly turn the ring to manual focus.

This is Nikon's second Micro-Nikkor in the DX lineup, after the AF-S DX Micro-NIKKOR 85mm f/3.5G VR which was announced third quarter 2009. The main differences between these lenses would be their focal length, physical size, aperture and the lack of VR in the 40mm. Another important factor of the 40mm is that it's priced at $279.95 USD, a full $250 less than the $529.95 USD 85mm Micro.

The 40mm (left) compared to the 85mm (right)

These images are not to scale. As you can evidently see, the 85mm is quite a bit larger.

The MTF charts compared. Again, 40mm is left and 85mm is right.

Looking at the lens design, you can see that the 85mm (right) features 14 elements in 10 groups and offers an ED (Extra Low Dispersion) element (shown in yellow), while the 40mm (left) features only 9 elements in 7 groups with no ED element. Another point to note is that the 40mm offers only a 7 bladed aperture diaphragm, while the 85mm offers a 9 bladed diaphragm, for smoother better rounded bokeh.

This lens seems like a bit of an oddball, it came as a bit of a surprise and the 40mm length is a bit strange for a micro lens. Of course, when you factor in the 1.5 crop, it becomes 60mm which is a much more common focal length, good for macro shots of flowers or as an all-purpose prime.

I guess that Nikon's attempt with this lens is to make the 60mm focal length available to DX users, or perhaps introduce day-to-day photographers to macro photography with a small, portable lens that doesn't break the bank.
Besides, the Tamron is larger, almost twice the price and gives an equivilant focal length of 90mm on a DX body. Of course, the f/2 aperture is helpful.

I'd love a wider angle macro lens myself, there's none in Canon-land, but there is one in Sony-land. If I was in Nikon-land, this would be a likely purchase although I'd prefer something a little wider still.

Specifically on the Tamron 60mm, it is reported to have a poor MF implementation, which is quite important in macro.

All I could think about when I saw this new less was: How's less than seven hundred bucks for an impressive set of Nikkor fast prime lenses? Sounds like a joke? Well, that's just what you'd spend if you bought the 35mm F/1.8, the 50mm F/1.8 and the new 40mm micro F/2.8.

If this new lens is up to the optical quality of the 35mm and 50mm, we are talking about a serius piece of equipment at a great price!

Besides, 60mm equiv is a great focal length for macro, I wouldn't get close to a bees nest with it, but for most other things it looks like a good choice for me, the more given that the 85mm is twice as costly.

Looking at the charts this should be a pretty sharp lens. As Baren mentioned, you could get this with the 35 and the 50 for under $700, which is a tremendous deal! You'd have your small, compact 40mm micro for quick flower shots, your 35mm for everyday shots of whatever and your 50mm for portraits.

As a noob in DSLR macro I was wondering about the lack of VR in this lens.
For the price is it a good trade off?
Considering that I will attempt most of the shots hand holding at a decent shutter speed or on a tripod.

The lack of VR shouldn't be a problem. Nikon's 60mm f/2.8 Micro doesn't have VR either and doesn't generally cause any inconvenience to people. For outdoors, you should be able to get quick shutter speeds hand held (otherwise I'd use a flash) so VR wouldn't really have too much of an effect, and otherwise you'd probably be on a tri-pod where using VR actually degrades the IQ.